This application claims the benefit of Japanese Application No. 139091/2000, filed May 11, 2000, in the Japanese Patent Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a device for recording information on an optical disc, and in particular, to a device and method of recording information on an optical disc while controlling an intensity of radiation of a light beam radiating on the optical disc so as to record the information.
2. Description of the Related Art
In a conventional device for recording information on an optical disc, an intensity of radiation of a light beam radiating on an optical disc is fed back to maintain the intensity of the radiation of the light beam as constant regardless of a temperature variation and the like.
FIG. 1 is a block diagram of the conventional device for recording information on the optical disc. In FIG. 1, an intensity of the radiation of a light beam (laser) radiating on the optical disc is fed back to maintain the intensity of the radiation of the light beam as constant. That is, the intensity of radiation of a laser radiated from a laser luminous element 59 is monitored by a laser output monitoring unit 54, a subtractor 55 compares a monitoring value output from the laser output monitoring unit 54 with a reference value outputted form a reference voltage generator 53, and the laser driver 58 controls an outputted driving current to conform with the two values and thereby maintain the intensity of radiation of the laser radiated from the laser luminous element 59 as constant.
Also, in the conventional recording device shown in FIG. 2, a reference voltage generator 53 outputs a reference value and the feedback loop is started through self operation, thereby starting the recording (writing) operation for the optical disc, if the recording signal output from a recording signal generator 51 is varied from a low (L) level to a high (H) level.
However, a predetermined time is required until the intensity of radiation of the light beam (laser) reaches the reference value after operating the feedback loop, since a response delay occurs in the feedback loop in the related art. That is, the intensity of radiation of the laser is still at a value smaller than the reference value just after the recording has started, because the feedback loop has just begun operating. So, the recording of the information is initially performed with an intensity of radiation of the light beam smaller than the reference value until the intensity of radiation of the light beam rises from the initial value to the reference value during the predetermined time. Specially, the intensity of radiation of the light beam is smaller than that intended for recording the information when the recording operation has just started.
Accordingly, there is a drawback in that the intensity of radiation of a light beam radiating on an optical disc does not reach the necessary intensity of radiation, resulting in the recording of information which is inferior in quality by producing errors in the recording of the information or non-recording of the information (non-recording areas).
It is, therefore, an object of the present invention to provide a device and method of recording information on an optical disc, which improves the recording quality of the information when the recording operation has just started.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and, in part, will be obvious from the description, or may be learned by practice of the invention.
To achieve the above and other objects, there is provided a device for recording information on an optical disc, comprising a luminous element radiating a light having recording information on the optical disc; a radiation intensity controller constantly controlling an intensity of radiation of the light radiating from the luminous element; a constant outputting unit providing a constant energy to the luminous element; a selector selectively selecting one of the outputs of the intensity of radiation controller and the constant outputting unit; wherein, the selector selects the constant outputting unit during a predetermined duration from a starting time of recording the recording information on the optical disc, and selects the intensity of radiation controller afterward.
It is desirable that the energy provided from the constant outputting unit to the luminous element is determined based on a testing record in the optical disc. Typically, an optical disc drive which records information on optical discs such as CD-R and CD-RW perform a test writing called optimum power control (xe2x80x9cOPCxe2x80x9d) to determine an optimal write power. The discs provide a testing area (OPC area). Although use of this area depends on the drive, a typical drive uses the area as follows.
A test writing is performed at some laser power. Then, the written signal is read and the power dependency of the signal quality is obtained. Then, the power of best quality is selected at the optimal power or the optimal power is calculated using extrapolation. A testing record in the optical disc is performed in the sequence mentioned above. Generally, the optimal power depends on the disc type and many drives perform the OPC before recording of the information when the disc is changed. In the present invention, a laser is driven with constant voltage for a predetermined period of time. The temperature dependence of the optimal power is small, but the laser character greatly changes according to the changing temperature. This means that the intensity of radiation at the predetermined period varies with the temperature. Avoiding this difficulty, the OPC is performed when the temperature varies over the predetermined level and the constant voltage level is then redetermined.
It is also desirable that the testing record is performed when a temperature detector equipped in the recording device detects a temperature variation.
To also achieve the above and other objects, there is provided a method of recording information on an optical disc by radiating a light provided from a luminous element, the method comprising providing a constant energy to the luminous element during a predetermined duration from a starting time of recording the recording information on the optical disc; and controlling an intensity of radiation radiating from the luminous element to be constant afterward.